Twin Speed Demons: Helios 1 and 2, the Fastest Human-made Objects Ever

In my last post, I talked about the fastest artificial object ever (within Earth's atmosphere): a 900 kilogram steel plate that, thanks to the kinetic energy provided by a nuclear blast, travelled at a speed of at least 66 kilometers per second. That's pretty darn fast.

However, there is one object that has travelled faster, and it is the subject of today's FactRoulette!

On January 15th, 1976, the second of two solar probes was launched from Cape Canaveral, Florida. Helios 2, along with the first probe, Helios 1, was designed to study solar processes (basically measuring output from our sun, monitoring sunspots, that sort of thing). They both were sent into heliocentric orbits (a heliocentric orbit being an orbit around the center of gravity of our solar system: basically, the sun), just inside the orbit of the innermost planet, Mercury. Helios 2 orbits about three million kilometers closer to the sun than Helios 1, and sits only 0.29 AU away from the sun (AU stands for "astronomical unit," and 1 AU is the average distance from Earth to the sun, or 149,597,871 kilometers).

One of the Helios probes undergoes testing before its launch into a heliocentric orbit.

In its slightly-closer orbit around our sun, Helios 2 became the fastest artificial object ever, orbiting at an incredible speed of 70.22 kilometers per second.

Interestingly enough, the missions of both probes ended in the early 1980s, but they sent back data to ground computers here on Earth until 1985. They are both currently non-functional, but they still orbit the sun, maintaining their break-neck speed as they circle our star over and over again.



Sources:

Wilkinson, John (2012), New Eyes on the Sun: A Guide to Satellite Images and Amateur Observation, Astronomers' Universe Series, Springer, p. 37
Solar System Exploration: Missions: By Target: Our Solar System: Past: Helios 2


Image:

"Helios - testing" by NASA/Max Planck - http://solarsystem.nasa.gov/multimedia/display.cfm?IM_ID=10624. Licensed under Public domain via Wikimedia Commons - http://commons.wikimedia.org/wiki/File:Helios_-_testing.png

"Like a Bat Out of Hell!" – The Fastest Artificial Object Ever (Inside Earth's Atmosphere)

If I were to ask you to imagine the fastest human-made object within Earth's atmosphere ever, what would you picture?

Perhaps something like this?

The ThrustSSC, with a land speed record of 1228 kph (763 mph). Yeah, that's pretty fast.

Or maybe something like this?

The Lockheed SR-71 Blackbird, holder of several manned-aircraft speed records.

Or perhaps this looks more like what you had in mind:

The launch of the space shuttle Atlantis, fast enough escape Earth's gravity; known as "escape velocity."

Whatever it is you imagined, I'm willing to bet that you didn't think the fastest human-made object looked like this:

Well, sort of like this. But much, much larger.

It's true! The fastest artificial object ever (inside Earth's atmosphere) is a large steel plate cover, weighing 900 kilograms (or 2000 lbs, if you prefer). Basically a huge manhole cover. How did this large hunk of metal become the fastest human-made object within Earth's atmosphere ever? This is where it gets quite interesting!

In 1957, a series of nuclear tests were carried out by the US government in Nevada. Named Operation Plumbbob, these tests were some of the most comprehensive nuclear tests ever undertaken. Most of the tests were to further the aim of weapons development, but some of them were designed as safety experiments. In one such test, code-named "Pascal-B," a nuclear weapon was detonated inside an underground shaft. Capping this shaft was the aforementioned steel plate. Dr. Robert Brownlee, the designer of the experiment, thought that a nuclear explosion would accelerate the plate to six times escape velocity–that is, the speed required for an object to escape the pull of Earth's gravity. Although a high speed camera was trained on the cap, it was only visible in a single frame following detonation. Regardless, the lower bound value for the plate's speed yielded by the video evidence was incredibly high. In the words of Dr. Brownlee, the video revealed the plate to be "going like a bat out of hell!"

It's possible that future space vehicles could be accelerated by detonating nuclear explosions against a "pusher plate," using the kinetic energy generated by successive blasts to bring the spacecraft up to speed.

You may have noticed that I qualified the record set by this unassuming steel plate with the phrase "within Earth's atmosphere." When I first posted this as a "today I learned" on my Facebook page, I mistakenly claimed that it held the record of being the fastest artificial object ever. However, after further reading, I discovered that there is one other man-made object that beats the record of our plucky little steel plate. These particular speed demons will be the subject of the next FactRoulette!



Sources:

Brownlee, Robert R. (June 2002). "Learning to Contain Underground Nuclear Explosions"
Pascal B test at the Nuclear Weapon Archive